Ok all done
For those technically minded, the server is now running NGINX to handle all the PHP and dynamic stuff, and Varnish CACHE on the server also.
Based on third party tests, the home page load time has gone from an average of 3 seconds to 1.2 seconds, and the cpu and ram usage has dropped by half
If you spot anything banjaxed, let me know Otherwise, hopefully, things should be a little nippier from now on.